Previous studies on the improvement of the performance of axially crushed tubes by the introduction of a filler material were based on the crushing of tubes filled with a low-density polyurethane foam [1]. Several design formulae related to foam-filled columns crushing have been suggested based on finite element simulations [2,3]. The mechanical behaviour of different types of foams used as fillers in aluminium tubular structures, under static and dynamic loading, has been studied extensively in the past few years [4]. Generally, there is a significant increase of the average crushing force and, in some cases, a change of the deformation behaviour is observed because of the interaction effect between the tube and the foam [5].

The results obtained by the authors are also analysed with respect to the length reduction and impact time, the effect of the connection between the foam and the outer skin, the energy decomposition, the influence of the skin material and impact velocity, and the influence of the shape of the cross-section on the impact behaviour.

In terms of the evolution of the strain energy the tests proved that there is unequivocal evidence for the existence of elastic deformation stages during the crushing of the tubular structures. It can be concluded that the increase in the strain energy can be associated to two main factors: the formation of lobes and elastic compression stages.

As for the influence of the shape of the cross-section on the energy absorbing capabilities, it can be seen that both the double-hat and the quadruple-hat sections lead to the highest decelerations. Thus, the high structural stiffness of these tubes leads to a low maximum length reduction and to relatively short impact times. Thus, these structural elements lead to situations where energy is absorbed mostly by plastic deformation of the outer skin and not of the metal foam core.

1

B.E. Lampinen and R.A. Jeryan, "Effectiveness of Polyurethane Foam in Energy Absorbing Structures", Society of Automotive Engineers, Inc., doc. n.^o 820494, 1983.

2

S. Santosa and T. Wierzbicki, "Crash behavior of box columns filled with aluminum honeycomb or foam", Computers and Structures, 68(4), 343-67, 1998. doi:10.1016/S0045-7949(98)00067-4

3

M. Seitzberger, F.G. Rammerstorfer, H.P. Degischer and R. Gradinger, "Crushing of axially compressed steel tubes filled with aluminium foam", Acta Mechanica, 125, 93-105, 1997. doi:10.1007/BF01177301

4

A.G. Hanssen, M. Langseth and O.S. Hopperstad, "Static and dynamic crushing of circular aluminium extrusions with aluminium foam filler", International Journal of Impact Engineering, 24(5), 475-507, 2000. doi:10.1016/S0734-743X(99)00170-0

5

A.K. Toksoy and M. Güden, "The strengthening effect of polystyrene foam filling in aluminum thin-walled cylindrical tubes", Thin-Walled Structures, 43, 333-350, 2005. doi:10.1016/j.tws.2004.07.007

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £75 +P&P)